1. Technical Field
The present disclosure relates generally to a window blind, and more particularly to a window blind which uses one single control module to adjust the inclination angle of the slats and to collect or expand the covering material.
2. Description of Related Art
By raising and lowering the covering material of a conventional window covering, the area to be shielded can be determined. The window coverings can be roughly divided into window blinds, cellular shades, roller shades, and sheer shades by the types or appearances of the covering materials. A window blind has a plurality of horizontally arranged long slats, which are suspended between a headrail and a bottom rail through ladder tapes. The area shielded by the slats can be adjusted by spacing the slats apart from top down or stacking the slats from bottom up. According to most people's habit of using a window covering, the purpose of collecting the covering material is to allow more light to pass through, and the purpose of expanding the covering material is to block light. Generally speaking, the bottom rail is often lowered to the lowest position, and the inclination angle of the slats can be adjusted to adequately change the amount of light passing through the covering material.
Window coverings can be also divided into two types by either a cord is used or not. Each type has its own way of operation. Window blinds having a cord can be further divided into three types: using at least one cord, using a cord loop, and specifically using a single cord. A conventional window covering using at least one cord includes a headrail, a bottom rail, and a covering material provided between the headrail and the bottom rail. An end of the cord is connected to the bottom rail, while another end thereof passes through the covering material and the headrail to be operated by the user. By general definition, the cord segment between the headrail and the bottom rail is a lifting cord, and the cord segment passing through the headrail for operation is an operation cord. By pulling the operation cord, the bottom rail can be operated to move for changing the area shielded by the covering material. If the exposed operation cord is looped, then such cord segment is called a cord loop. The location of the bottom rail can be changed by pulling the front side or the rear side of the looped operation cord. A window covering which uses a cord loop usually has a rotatable shaft tube or shaft provided in the headrail. The covering material can be collected or expanded by pulling the cord loop to drive the shaft tube or the shaft, which rolls up or releases the covering material or the lifting cord. As for the type of using one single cord, there is, apparently, only one operation cord exposed from the headrail. This type of window coverings can be further divided into two types by whether the operation cord is retractable or not. If the operation cord is not retractable, the operation of the window covering using the single cord is similar to those having at least one cord. On the other hand, the covering material of a window covering, which has a retractable operation cord, can be collected by pulling and releasing the operation cord repeatedly.
As mentioned above, the covering material of a conventional window blind can be collected or expanded by operating the operation cord to move the bottom rail upward or downward. In addition, another adjustment mechanism is required to change the inclination angle of the slats. More specifically, a ladder tape includes two warps, and such an adjustment mechanism is capable of moving upward one warp and moving downward the other warp at the same time to adjust the inclination angle. In other words, a conventional window blind has two independent mechanisms, one of which is used for collecting and expanding the covering material, and the other one is used for adjusting the inclination angle of the slats. Such design is very inconvenient to use. Some manufacturers have tried to integrate these two mechanisms into one single control module, as disclosed in Taiwanese Patent Publication No. M269349 and M356795. However, both the disclosed single control modules include a lifting cord passing through all slats, which means the lifting cord is located between two warps. While adjusting the inclination angle of the slats, any two vertically adjacent slats would not be able to tightly abut against each other, leading to the problem of light leakage. Therefore, the window blind which has one single control module still has room for improvements.